async attribute | async property

Provides control of when a script executes while a document loads. Setting a script to run asynchronously can improve performance by unblocking the rest of the document. When async = false, it can preserve execution order to ensure dependent scripts are run in order.

This property is read/write.

Syntax

HTML

<element async="ptr" ... >

JavaScript

object.async = ptrptr = object.async

Property values

Type: boolean

When true, the script will execute asynchronously, otherwise script is executed as page loads.